The way that the Vietnam War is now remembered as the helicopter war, the current conflicts in Iraq and Afghanistan may be remembered for the use of unmanned aerial surveillance (UAV) craft or drones. Drones may facilitate remote intelligence gathering, alleviating the need for foot soldiers to enter into hostile areas “blind,” with little or no information about the location and strength of hostile forces. Drones may provide close combat support, such as identifying and eliminating targets of interest, alleviating the need to expose soldiers and/or airmen to potential small arms fire, mortars, rocket grenades, road-side bombs, anti-aircraft weaponry, missiles, and other dangers.
Although many presently used drones are the roughly the same scale size as piloted aircraft, such aircraft are both relatively expensive and may be detected due to their size. Recently, smaller drones have been developed that may be deployed in greater numbers and are relatively less expensive resulting in greater use by individual units in the field. Smaller drones have certain tradeoffs as they cannot carry the amount of payload of a larger drone. Further, power for such smaller drones is limited due to the size of the aircraft and therefore operating periods are also limited.
Unmanned drone aircraft typically mount a camera in a ball turret assembly which allows movement in three dimensions to allow the camera to track objects on the ground without altering the flight path of the aircraft. Data such as image data may be captured via a sensor such as a camera and transmitted back to a controller. Known ball turret assemblies use a pan tilt mechanism with a cylindrical or spherical turret to mount a sensor such as a camera. Such devices are suspended from the bottom of the aircraft via a fork shaped yoke that may be rotated around a roll axis via a roll actuator. The tilt motion of such a turret starts from zero degrees pointing the camera straight down to a 90 degree positive or negative tilt pointing the camera in the direction of the flight of the aircraft. Thus, such arrangements traditionally have a roll axis that is vertical and a tilt axis is 90 degrees offset from the roll axis.
Current turret designs require gimbals and mounting structures that present a relatively large cross-profile. Thus, drag based on the turret mounting for known turret designs is a consideration especially when drag decreases fuel efficiency and decreases operational range. Such increased drag is a significant factor in limiting the range of smaller drones that have limited power supplies. Further, for certain important viewing areas such as the area directly below the aircraft, the gimbal is locked and therefore panning to the right or left is more difficult to access using the traditional actuators because the tilt simply rotates the turret toward the front or rear of the aircraft. Thus panning right or left requires rotating the turret on the roll axis and then tilting the turret. As with all components, fewer moving parts are desirable and this is especially true with smaller drones where the efficiency of the payload needs to be maximized. Ideally, the portion of the coverage affected by gimbal lock should be an area that is less important or not important at all. As explained above, current gimbal designs put gimbal lock either directly below the aircraft, or point them directly forward and therefore gimbal lock effects relatively important viewing areas.
A further issue is the wiring needed to power and draw data from sensors such as cameras in the ball turret. In known ball turret assemblies, such wiring inhibits the full range of movement of the camera on the ball turret resulting in limited vision. For example, if the turret is rotated to view the area directly below the aircraft, the movement is constrained by the electrical wiring which does not allow the ball to be rotated fully. Since it is desirable for the turret to be rotated fully, conventional mountings substitute a brush interface (a slip ring) for physical wiring which limits the bandwidth thereby limiting data transmission.
Thus, it would be desirable to have a ball turret mounting system to minimize cross-section and thereby minimize drag. It would also be desirable to have a mounting system for a ball turret that allows efficient actuators for maximum coverage for cameras in the ball turret. Also, it would be desirable to provide a physical wired connection to provide greater data bandwidth.